my 1989 gmc s15 just started to suck gas bad.

1989 gmc 4.3 mpgs dropped bad. lost about 40 -50 miles per tank. nothing done before that started. was running ok, had a rough idle but was getting decent mpgs. so far i have replaced the ignition coil and egr valve, but after replacing egr valve it started to sputter at take off. egr purchased at autozone. dont want to start replacing parts. so if you guys have any pointers, they would be very appreciated.

5 Answers

Many times the O2 sensors get slow and weak with age and can
cause a big loss in the mpg department. Normally they should
be replaced at 100,000 miles. Now don't run out and buy O2
sensors just yet. If it was me I would have your truck scanned for
fault codes. I think your truck has throttle body injection and
there could be an issue with the fuel injector. Report back with
any codes that show up during the scan.

follow up on y 89 gmc s15, with 4.3V6. replaced egr valve and
started to sputter, replaced o2 sensor and started running good,
but as soon as it warmed up it sputtered again on take off.
Installed old egr valve and sputter went away. replace fuel pump
just cause of the high miles and im not sure of the history of the
truck. runs good but still seems to be burning more fuel. no cel
and driving me F#@(ING nuts. any suggestions will be very
appreciated. thanks

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1989 gmc 4.3 mpgs dropped bad. lost about 40 -50 miles per tank. nothing
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